通风报信

Explanation: The opposing sides in the dark, the other party's Confidential. 　　Usage: Joint type; as predicate; refers to secretly pass messages 　　Source: Qing Yi Suo "Yellow Hydrangea" 20 back: "That the treasurer said he was vicious, with the hand to send the coffin to the Chen government called up the tipped off to one side possidetis this dispensers, including the guards." 　　Examples: He immediately turned around, copied across the alley back to Aunt Sin bamboo huts going to give it a few party members ~. (Ouyang Shan "Sanjiaxiang" xxvi)